CN111295564A

CN111295564A - Optical wheel evaluation

Info

Publication number: CN111295564A
Application number: CN201880070315.XA
Authority: CN
Inventors: Z·F·米安; R·W·伽玛彻
Original assignee: International Electronic Machines Corp
Current assignee: International Electronic Machines Corp
Priority date: 2017-09-15
Filing date: 2018-09-14
Publication date: 2020-06-16
Also published as: US11320371B2; WO2019055795A1; EP3682189A4; CA3093673A1; EP3682189A1; US20200408682A1

Abstract

Evaluation of a spinning wheel is described. The evaluation utilizes information obtained by reflecting radiation off one or more areas of the rotating wheel. The imaging device may acquire image data that is processed to evaluate the wheel. The radiation may comprise diffuse and/or coherent radiation. Image data of substantially the entire circumference of the wheel may be used in the evaluation.

Description

Optical wheel evaluation

Reference to related applications

The current application claims the benefit of co-pending U.S. provisional application No.62/559,029 filed on 2017, 9, 15, which is incorporated herein by reference.

Technical Field

The present disclosure relates generally to the evaluation of wheels, and more particularly to a solution for optically measuring wheels.

Background

Current round Measurement solutions, such as those described in U.S. Pat. No.5,636,026 entitled "Method System for contact measuring of Railroad Wheel Characteristics" and U.S. Pat. No.6,768,551 entitled "contact Wheel measuring System and Method", both hereby incorporated by reference, effectively measure various attributes of a round. For example, when measuring a rail wheel, attributes such as rim thickness, rim height, reference wheel well diameter (when available), wheel diameter, and wheel angle of attack may be measured to ensure that continued operation of the wheel remains safe.

Embodiments of these solutions may not provide an effective solution for measuring other wheel attributes (such as the surface topography of the tread surface) that may be used to determine other defects that may affect the operational condition of the wheel. For example, a wheel that includes flat spots or is sufficiently out of round (e.g., oval) or includes one or more grooves, cracks, shelled areas, etc. may be undesirable for continued operation. U.S. patent No.7,564,569, which is incorporated herein by reference and is entitled "Optical WheelEvaluation," describes several methods of achieving this goal.

Disclosure of Invention

In view of the above, the inventors have recognized a need for an improved optical evaluation solution that can accurately measure one or more wheel attributes for which current solutions may not provide adequate and/or sufficiently accurate measurements. Advances in technology, and in particular the availability of ultra-high speed smart cameras, have enabled new methods of optically measuring wheel flaws at higher speeds, with improved resolution, and with improved wheel defect coverage. The inventors have found that it is advantageous to combine multiple techniques to optimally address all wheel defects of interest.

Aspects of the present invention provide a solution for optically evaluating a wheel along at least one circumference of the wheel. However, it is understood that in certain applications, such as where transit train traffic of the same vehicle is frequently checked in short time frames, data that is valued for the entire perimeter may be obtained by capturing and stitching (stitch) partial perimeter data acquired by the vehicle through the system during any given trip without departing from the illustrative embodiments of the invention described herein. The evaluation utilizes information obtained by reflecting radiation off one or more areas of the rotating wheel. The imaging device may acquire image data that is processed to evaluate the wheel. The radiation may comprise diffuse and/or coherent radiation. Image data of substantially the entire circumference of the wheel may be used in the evaluation.

In an embodiment, the image data is obtained while the wheel is moving along a path having a length of at least one circumference of the wheel. Moreover, those skilled in the art will recognize that the path may be in-situ (in place) linear travel or circular travel without departing from the intent behind the invention. The path and/or wheel may be illuminated to enhance the resulting image data. One or more attributes of the wheel are measured based on the image data. The attributes may then be used to detect one or more defects in the wheel. In one embodiment, the wheel is a railroad wheel, the wheel is illuminated, and the illuminated wheel is imaged by one or more cameras. However, it is understood that other types of wheels, tires, round support members, cylinders (cyclinders), etc. may be measured without departing from the intent underlying the present invention.

A first aspect of the invention provides a method of evaluating a wheel, the method comprising: illuminating a path of the wheel, wherein a length of the path includes at least one circumference of the wheel; obtaining image data of the wheel as the wheel moves along the path; and measuring at least one property of the wheel based on the image data. By path it is understood that the wheels may roll along the path as part of the vehicle, be mounted on the vehicle to inspect the wheels on the vehicle or be rotated in place in the measuring machine. Many other paths are conceivable, which are obvious variants of the simple paths described above.

A second aspect of the invention provides a system for evaluating a wheel, the system comprising: means for illuminating a path of the wheel, wherein the extent of the path includes at least one circumference of the wheel; means for obtaining image data of the wheel as the wheel moves along the path; and means for measuring at least one property of the wheel based on the image data. Also, the wheels may be measured by a system installed on a train vehicle, or installed on the side of a track, or installed in a wheel repair shop, without departing from the invention.

A third aspect of the invention provides a method of generating a system for evaluating a wheel, the method comprising: obtaining a computer infrastructure; and deploying a means for performing one or more of the steps described herein to a computer infrastructure.

A fourth aspect of the invention provides a method of evaluating a wheel, the method comprising: illuminating an area in which the wheel is rotating, wherein the illumination comprises at least one light sheet (sheet of light), wherein each light sheet is configured to intersect a side surface of the wheel, thereby forming a chord on the side surface, and to intersect a tread surface of the wheel on at least one side of the chord, wherein at least one of: the chord is positioned at a substantially constant distance from the centre of the wheel as the wheel rotates in this region, or the chord forms a segment with a substantially constant height on the side surface of the wheel as the wheel rotates in this region; obtaining image data of the wheel as the wheel rotates in the region, wherein the image data includes a plurality of images acquired at different times when the wheel is positioned within the region, wherein the plurality of images includes a plurality of images of a region of a tread surface of the wheel that intersects at least one of a set of rays (line of light); and evaluating the tread surface of the wheel based on the image data.

A fifth aspect of the invention provides a system for evaluating a wheel, the system comprising: a set of lighting devices configured to illuminate an area in which the wheel is rotating, wherein the set of lighting devices emits at least one light sheet configured to intersect a side surface of the wheel, thereby forming a chord on the side surface, and to intersect a tread surface of the wheel on at least one side of the chord, wherein at least one of: the chord is positioned at a substantially constant distance from the centre of the wheel as the wheel rotates in this region, or the chord forms a segment with a substantially constant height on the side surface of the wheel as the wheel rotates in this region; a set of imaging devices configured to acquire image data of the wheel as the wheel rotates in the region, wherein the image data includes a plurality of images acquired at different times while the wheel is positioned within the region, wherein the plurality of images includes a plurality of images including a region of a tread surface of the wheel that intersects at least one of the set of rays; and means for evaluating the tread surface of the wheel based on the image data.

A sixth aspect of the invention provides a system for evaluating a wheel, the system comprising: a set of lighting devices configured to illuminate at least a tread surface of a wheel with diffuse radiation; a set of imaging devices configured to acquire image data of the wheel as the wheel rotates in the region, wherein the image data includes a plurality of images acquired at different times while the wheel is within the region, wherein the set of imaging devices acquires image data including portions of the tread surface glancing off of diffuse radiation; and means for evaluating the tread surface of the wheel based on the image data.

Other aspects of the invention provide methods, systems, program products, and methods of using and generating each of them, which include and/or implement some or all of the actions described herein. The illustrative aspects of the present invention are designed to solve one or more of the problems herein described and/or one or more other problems not discussed, which may be present in the art.

Other aspects of the invention taught in U.S. patent 7,564,569 entitled "Optical Wheel Evaluation" are not repeated in the present description.

Drawings

These and other features of the present disclosure will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various aspects of the invention.

FIG. 1 shows a schematic view of an illustrative environment for evaluating a wheel, according to an embodiment of the invention.

Fig. 2 shows a partial cross-sectional view of an illustrative guide wheel.

Fig. 3A-3C illustrate various deficiencies of a guide wheel.

Fig. 4A and 4B show perspective and side views, respectively, of an illustrative environment for evaluating a rail wheel, according to an embodiment.

Fig. 5 shows an illustrative environment including an alternative illumination configuration for obtaining image data of a guide wheel and a guide rail, according to an alternative embodiment.

Fig. 6 shows an illustrative environment including another alternative illumination configuration for obtaining image data of a guide wheel and a guide rail according to an embodiment.

FIG. 7 shows detection of a wheel in an image acquired by an imaging device in an illustrative environment according to an embodiment.

8A-8C illustrate detection of features in an image of a wheel according to an embodiment.

Fig. 9 illustrates an alternative embodiment showing a system deployed in a wheel repair shop.

It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.

Detailed Description

As indicated above, aspects of the present invention provide solutions for optically evaluating a wheel along at least one circumference of the wheel. In an illustrative embodiment, the image data is obtained as the wheel moves along a path having a range of at least one circumference of the wheel. The wheel may be illuminated to enhance the resulting image data. One or more attributes of the wheel are measured based on the image data. The attributes may then be used to detect one or more defects in the wheel. In one embodiment, the wheel is a railway wheel and the wheel segments are illuminated as the wheel surface moves along the path.

Turning to the drawings, FIG. 1 shows a schematic view of an illustrative environment 10 for evaluating a wheel, according to an embodiment of the invention. In this regard, the environment 10 includes a computer infrastructure 12 that can perform the various process steps described herein for optically evaluating a wheel. In particular, computer infrastructure 12 is shown to include a capture system 30 for capturing wheel data 50 based on the wheel and computing device 14 including a processing program 40, processing program 40 enabling computing device 14 to measure the wheel by performing the process steps of the invention.

In general, capture system 30 is shown to include a detection module 32, an illumination module 34, an imaging module 36, and a transmission module 38, where each module includes one or more devices for performing a corresponding function. For example, the detection module 32 may include one or more devices for detecting the presence of the wheel and/or one or more attributes of the wheel (such as speed, brightness, load, etc.). The illumination module 34 may include one or more devices for illuminating the path of the wheel and/or a portion of the wheel, such as a laser line generator, a thermal heater that generates a heated portion of the wheel, a multi-spectral illuminator, an x-ray source illuminator, an ultrasonic energy-based illuminator, a visible light source, and so forth. The imaging module 36 may include one or more devices, such as a camera, for sensing energy of the illumination returned to the imaging module 36 (e.g., reflections obtained from the wheel) and generating image data based on the sensed reflections. Transfer module 38 may include one or more devices for transferring image data and/or other data about the wheel to computing device 14 for storage as wheel data 50 and/or processing by computing device 14 when executing processing program 40.

Computing device 14 is shown including a processor 20, a memory 22A, an input/output (I/O) interface 24, and a bus 26. In addition, computing device 14 is shown in communication with external I/O devices/resources 28 and storage system 22B. As is known in the art, in general, processor 20 executes computer program code, such as processing program 40, that is stored in memory 22A and/or storage system 22B. While executing computer program code, processor 20 may read from and/or write data, such as wheel data 50, to memory 22A, storage system 22B, and/or I/O interface 24. Bus 26 provides a communication link between each of the components in computing device 14. I/O devices 28 can include any device that enables user 16 (e.g., a human user or a system user) to interact with computing device 14 and/or any device that enables computing device 14 to communicate with one or more other computing devices included in computer infrastructure 12, such as transport module 38.

In any case, computing device 14 can comprise any general purpose computing article of manufacture capable of executing computer program code installed thereon (e.g., a personal computer, server, handheld device, etc.). In addition, computing device 14 may include specially designed ruggedized devices, embedded digital signal processing devices, and the like. However, it should be understood that computing device 14 and processing program 40 are only representative of various possible equivalent computing devices that may perform the various processing steps described herein. In this regard, in other embodiments, the computing device 14 may comprise any specific purpose computing article of manufacture comprising hardware (with or without computer program code) for performing specific functions, any computing article of manufacture that comprises a combination of specific purpose and general purpose hardware/software, or the like. In each case, the program code (when included) and hardware can be created using standard programming and/or engineering techniques, respectively.

The capture system 30 communicates with the computing device 14 over the communication link 18. The communication link 18 may comprise any combination of various types of wired and/or wireless communication links. In this regard, the communication link 18 may include any combination of one or more types of networks (e.g., the Internet, a wide area network, a local area network, a virtual private network, etc.). In one embodiment, capture system 30 communicates with computing device 14 using a one-to-one wired connection such as Universal Serial Bus (USB), ethernet, or the like. Regardless, the communication between the capture system 30 and the computing device 14 may utilize any combination of various types of transmission techniques and/or communication protocols.

As previously mentioned and discussed further herein, handler 40, when executed on computing device 14, enables computing infrastructure 12 to evaluate the wheel based on wheel data 50 received from capture system 30. In this regard, the processing routine 40 is shown to include a calibration module 41 for calibrating one or more attributes of the capture system 30, an adjustment module 42 for adjusting one or more attributes of the image data, and a measurement module 44 for calculating one or more measurements of the wheel. In addition, the processing routine 40 is shown to include a defect module 46 that determines whether one or more defects exist in the wheel and a condition module 48 that determines whether the wheel is safe for continued use. The operation of each of the capture system 30 and the handler 40 and their corresponding modules are discussed further herein. However, it should be understood that some of the various modules shown in FIG. 1 can be implemented independently, combined, and/or stored in memory for one or more separate computing devices that are included in computer infrastructure 12. Additionally, it should be understood that some of the modules and/or functionality may not be implemented, or additional modules and/or functionality may be included as part of environment 10.

Regardless, in an illustrative embodiment, embodiments of the present invention provide a solution for evaluating a wheel through the use of electromagnetic energy (such as light energy). It should be understood that while illustrative embodiments of the present invention are shown and described as performing optical evaluations using image data generated based on visible light, embodiments of the present invention may use image data generated based on electromagnetic radiation including wavelengths in one or more portions of the electromagnetic spectrum. In this regard, alternative embodiments of the present invention may generate image data based on reflections of a wheel illuminated with electromagnetic radiation in one or more of the visible portion(s), infrared portion, near infrared portion, ultraviolet portion, X-ray portion, etc. of the electromagnetic spectrum. Additionally, image data may be generated based on other non-electromagnetic radiation based illumination solutions (such as acoustic signals, sonar signals, magnetic field interference, etc.). In embodiments of the present invention, the lighting module 34 may not be included as part of the environment 10.

In one embodiment, environment 10 is used to measure various characteristics of the rail wheel. For example, fig. 2 shows a partial cross-sectional view of an illustrative guide wheel 60. In general, the rail wheels 60 may be used on locomotives, railway vehicles, and/or any other vehicle that rides on one or more rails 62. It should be understood that the guide wheels 60 are merely illustrative of various types of guide wheels and non-guide wheels. Various attributes/characteristics of the guide rail wheel 60 may be measured by embodiments of the computing infrastructure 12 (fig. 1) described herein. For example, attributes of the guide wheel 60 such as diameter/radius, rim height, reference well radius, rim thickness, and the like may be measured. Furthermore, defects in the wheel, such as hot cracks, flat spots, out of round, etc., may be measured. Similarly, any desired attribute of the non-rail wheel may be measured using embodiments of the present invention. In this regard, aspects of the present invention are not limited to measuring any type of one or more properties for a particular rail/non-rail wheel 60.

In any event, the rail wheel 60 is shown as being supported by a rail 62 and includes a field side 64 and a gauge side 66. Generally, the field side 64 faces outwardly from the pair of rails 62, while the gauge side 66 faces inwardly from the pair of rails 62. Adjacent to the rail 62, the rail wheel 60 includes a field side rim face 68, a tread surface 70, a flange 72, and a gage side rim face 74. During normal operation, the rail wheels 60 contact the rail 62 along the tread surface 70 and rotate about the centerline 76, while the rim 72 prevents the wheels from moving away from the rail 62 due to the outward forces present during normal operation. Thus, the interaction between the rail wheels 60 and the rails 62 causes wear of the tread surface 70 and the rim 72.

The uneven interaction between the guide rail wheel 60 and the guide rail 62 may create one or more defects in the guide rail wheel 60. For example, fig. 3A shows an illustrative rail wheel 60A in which the tread surface 70A includes flat spots 80. The flat spot 80 may be caused by, for example, a continuous locking of the braking system. Additionally, fig. 3B shows an illustrative rail wheel 60B that includes out-of-roundness (OOR) defects due to the elliptical (e.g., oval) shape of the tread surface 70B and/or the rim 72B, which may be caused by uneven interaction due to improper installation of the wheel 60B and/or improper positioning (e.g., off-center) of the center hole of the rail wheel 60B. Still further, chipping, heat, manufacturing defects, etc. can create flat spots 80, out of round rail wheels 60B, and/or one or more additional defects, such as cracks (e.g., hot cracks), gouges, shelling areas, etc. In this regard, fig. 3C shows an illustrative rail wheel 60C in which the gauge-side rim face 74C includes narrow furrows 82 and wider defects (such as thermal cracks 84). It should be understood that the various defects shown in fig. 3A-3C are merely illustrative of various possible defects of the guide rail wheels 60A-60C that may be detected using the present invention. In addition, it is understood that various defects are shown in an exaggerated manner for clarity. In practice, the invention can be used to detect defects of much smaller but in principle identical guide wheels 60A-60C.

Fig. 4A and 4B show perspective and side views, respectively, of an illustrative environment 10A for a measurement rail wheel 60, according to an embodiment. In general, as the guide wheels 60 travel through the environment 10A, the guide wheels 60 may move in either direction while being supported by the guide rails 62. The environment 10A may include one or more detection modules 32 that may be positioned and operated in a manner to detect the presence of the rail wheels 60 approaching the

housings

90A, 90B from one or either direction. Each

housing

90A, 90B may comprise any type of reinforced weather-resistant housing and may be secured to ballast (ballast), railroad ties (railroadties), rails, and/or concrete using any solution. The

housings

90A, 90B may be located on the field side, gauge side, or both sides of the rail, depending on the requirements of the application. Regardless, each

enclosure

90A, 90B may be configured to protect one or more components of environment 10A from harmful exposure to the surrounding environment in which the components are deployed (e.g., weather, impact (impact), etc.). It should be understood that the

enclosures

90A, 90B are not necessarily required for all applications in which the environment 10A may be utilized, such as for example, for use of the environment 10A in a controlled environment (such as a factory, a maintenance shop, etc.).

In general, the illumination module 34 (FIG. 1) includes one or more illumination devices, while the imaging module 36 (FIG. 1) includes one or more imaging devices. In this regard, the

housings

90A, 90B are shown to include a plurality of illumination/imaging device pairs, such as an illumination device 94 and an imaging device 96, each of which may be attached to the

housings

90A, 90B using any solution. Also advantageously, where imaging is performed by the camera 96 in the housing 90B, the illuminator 94 may be attached to a rail, railroad tie, or the like.

In operation, the detection module 32 senses the presence of the rail wheel(s) 60 and generates a signal that is sent to the illumination device 94 and the imaging device 96. In response to the signal, each illumination device 94/imaging device 96 operates to obtain image data of the rail wheel 60 and the rail 62. The detection module 32 may also sense the speed at which the guide wheel 60 is traveling. In this case, the operation of the illumination device 94 and/or the imaging device 96 may be adjusted based on the speed. For example, environment 10A may be configured to track wheel 60 moving at speeds up to approximately fifty miles per hour (eighty kilometers per hour) depending on the particular lighting device 94 and imaging device 96 processing. Based on the actual speed of the rail wheel 60, the amount of time the illumination device 94 illuminates the area through which the rail wheel 60 will travel may be adjusted, and/or the number of images per second that may be captured by the imaging device 96 may be adjusted to obtain a desired resolution, thereby saving system resources (e.g., memory) for the slower moving rail wheel 60. In addition, when the rail wheel 60 is detected to move faster than a maximum speed, the illumination device 94 and/or the imaging device 96 may remain idle while the rail wheel 60 passes. In this case, an error code or the like may be generated by the detection module 32. Additionally, the detection module 32 may sense the brightness of the rail wheel 60, and the operation of the illumination device 94 and/or the imaging device 96 may be adjusted in a known manner based on the brightness.

It should be appreciated that various solutions may be implemented to adjust the amount of time each illumination device 94 and/or imaging device 96 operates in imaging the rail wheel 60. In one embodiment, the detection module 32 signals the guide wheel 60 that the first illumination device 94 and/or the first imaging device 96 will pass. In response, the first imaging device 96 may be activated and begin imaging the rail wheel 60. Using the image data, the imaging module 36 (fig. 1) may determine when the rail wheel 60 has reached a particular point (e.g., spanning seventy percent) in the field of view of the first imaging device 96. Once this point is reached, the imaging module 36 may activate the next illumination device 94 and/or imaging device 96 that begins imaging the rail wheel 60. Subsequently, the previous imaging device 96 may be turned off when the imaging module 36 determines that the rail wheel 60 has left its field of view and/or when the imaging module 36 determines that the rail wheel 60 has reached a particular point in the field of view of the next imaging device 96. In either case, only two imaging devices 96 will be operating at any one time, thereby reducing the power requirements on the system at any one time.

As shown in fig. 4A and 4B, the environment 10A may include a plurality of illumination device 94 and imaging device 96 pairs located on the interior side of the rail 62. For example, the housing 90A is shown to include eight pairs of illumination devices 94 and imaging devices 96 for acquiring image data for each of the guide wheels 60. In particular, each rail wheel 60 may be imaged by up to four imaging devices 96 as each rail wheel 60 passes through the environment 10A. Although each

housing

90A, 90B is shown as including four illumination device 94 and imaging device 96 pairs, it should be understood that any number of pairs located inside and/or outside the rail may be utilized. Further, only a subset of the pairs of illumination devices 94 and imaging devices 96 may be operated to image the rail wheel 60 as the rail wheel 60 moves through the environment 10A.

In one embodiment, the lighting device 94 located between the rails projects electromagnetic radiation (such as one or more laser lines) onto the rail 62 and gauge side 66 (fig. 2) of the rail wheel 60 as the rail wheel 60 moves along the rail 62. An imaging device 96 located between the rails captures image data, such as one or more images, of the rail wheels 60 and the rails 62 based on the reflection of the electromagnetic radiation when the rail wheels 60 are within the corresponding fields of view. The image data is then communicated to computing device 14 (FIG. 1) for processing by processing system 40 (FIG. 1). Embodiments in which the housing 90A is disposed between rails are more fully described in the teachings of U.S. patent 7,564,569 entitled "Optical Wheel Evaluation," and is not described in further detail herein.

It is understood that environment 10A is only illustrative of various possible alternative environments. For example, although only a single detection module 32 is shown, a second detection module may be located on the other side of the

housings

90A, 90B to sense the rail wheels 60 approaching from the opposite direction. Further, the relative positions of the

housings

90A, 90B and the detection module 32 as illustrated are merely illustrative and may be changed as desired. In any case, it is understood that the detection module 32 must be positioned a sufficient distance from the

housings

90A, 90B to provide sufficient time to prepare the illumination device(s) 94 and/or imaging device(s) 96. Such distance will vary based on, for example, the maximum speed at which the guide wheels 60 may travel through the environment 10A.

Further, while multiple illumination device 94/imaging device 96 pairs are shown, it is understood that any number (e.g., one or more) of illumination devices 94 and/or imaging devices 96, paired or unpaired, may be used. For example, a single illuminator 94 may be provided, the single illuminator 94 directing radiation at the rail wheel 60 as the rail wheel 60 passes along the rail 62 and the rail wheel 60 is imaged by more than one imaging device 96. In addition, only the rail wheels 60 on a single rail 62 may be imaged, and/or the rail wheel(s) 60 may be imaged from both the field side 64 (fig. 2) and the gage side 66 (fig. 2). In this regard, while the environment 10A is shown as including a single housing 90B configured to image the field side 64 of one of the rail wheels 60, it is understood that the environment described herein may include a second housing on an opposite side of the rail 62 for imaging the field side of the other rail wheel 60. Further, depending on the type of image data of the rail wheel 60 that is desired to be acquired and analyzed, the imaging device(s) 96 located outside the rail 62 may be configured to acquire image data of the gauge side of the rail wheel 60 located on the opposite rail 62 and/or the environment may be achieved without one or more of the

housings

90A, 90B.

In an embodiment, the rail wheel 60 traveling through the environment 10A is imaged by the imaging device(s) 96 over a distance comprising at least one full turn (revolution) of the rail wheel 60. In this regard, the illumination device(s) 94 and/or the imaging device(s) 96 may be configured to illuminate and/or image a distance along the rail 62 that is at least the circumference of the largest wheel to be imaged. The actual distance illuminated and/or imaged may be kept constant (in which case the smaller guide wheel 60 is imaged on more than one turn), or adjusted based on the actual size of the guide wheel 60. Regardless, it should be understood that multiple wheels (such as rail wheels 60) may need to be imaged simultaneously, e.g., two adjacent rail wheels 60 may be spaced apart by a distance less than the circumference of each wheel. In this regard, the illumination device(s) 94 and/or the imaging device(s) 96 may be capable of illuminating and/or imaging multiple wheels simultaneously.

However, it is understood that this need not be the case. For example, in the case of repeated rail traffic that is normal, e.g., the same vehicle passes through the environment multiple times a day or week, then the following would likely occur: even if only a portion of the circumference is examined at any single time, the entire circumference will be examined over time. In this regard, in situations where the transit train traffic of the same vehicle is frequently checked in short time frames, embodiments of the environment described herein may obtain data that is valued for the entire perimeter in a relatively short duration by capturing and stitching portions of the perimeter data acquired during any given trip through the environment. The partial perimeter image capture method may, for example, provide significant cost savings for smaller passes that are also satisfactory in capturing an entire perimeter, for example, over an entire day, and analyzing images of partial or full perimeters.

Fig. 5 shows an illustrative environment 10B that includes an alternative illumination configuration for obtaining image data of the guide wheels 60 and the guide 62, according to an embodiment. In this case, the illumination device 94 and the imaging device 96 are located on the field side of the rail 62. In an embodiment, referring to fig. 4A-5, the one or more illuminators 94 generate a plurality of light sheets arranged such that each sheet is at a favorable angle relative to the horizontal, such as light sheet 100 along the path of the rail wheel 60 shown in fig. 5. For example, when the rail 62 is substantially horizontal, the projection axis of the illuminator 94 may be set substantially horizontal such that the light sheet intersects the wheel at a fixed position having a fixed height relative to the rail 62 as the wheel 60 moves along the rail in the direction D. The plurality of light sheets 100 are projected on the wheel 60 over a total distance C that is greater than or equal to one full turn of the rail wheel 60 (i.e., at least one circumference of the rail wheel 60).

Where light sheet 100 intersects wheel 60, light rays 102 are formed along the field side of wheel 60 and the tread surface. As the wheel 60 moves along the rail 62 in direction D, the horizontal axis of the light sheet 100 will always intersect the wheel 60 at the same height above the wheel 62, creating a line 102 imaged by the imaging device 96. In this regard, each light sheet 100 may form a chord on the field side of the rail wheel 60 that forms a segment having a substantially constant height on the field side of the rail wheel that generally corresponds to the height of the light sheet 100 above the rail 62. The chord formed on the field side of the guide wheel 60 may be processed to identify the end position of the light ray 102 formed on the tread surface and/or to determine one or more properties of the wheel (e.g., the diameter of the wheel, the presence of a flat spot, the presence of defect(s) on the field side, etc.). Although only a single light sheet 100 and corresponding light ray 102 are shown for clarity, it is understood that multiple parallel light rays 102 may be simultaneously generated on the wheel 60.

The imaging speed of the imaging device 96 may be adjusted based on the speed of the wheel 60 to produce a desired spatial resolution on the surface of the wheel 60 as the wheel 60 moves along the path D. For example, in successive images, the light rays 102 may be spaced apart along the tread surface of the rotating wheel 60 by about one-eighth of an inch (e.g., three millimeters) or less to provide resolution for identifying defects typically desired in the railroad industry. It is understood that higher or lower resolution may be obtained by operating the imaging device at higher or lower speeds, respectively.

For each ray 102 formed on the guide wheel 60, the corresponding image data for the ray 102 will be different because the image is obtained from a different location on the wheel 60. The distance between successive light rays 102 may be determined by the speed of the imaging device 96 and the speed of the wheel 60 along the rail 62.

It is understood that the use of a substantially horizontal projection of the light sheet 100 is only one laser-based solution for illuminating the rail wheel 60. For example, as taught in U.S. patent No.7,564,569, substantially perpendicular rays of light may be projected onto wheel 60 from an illuminator on the gauge side of the rail and below the top of the rail and imaged by an imaging device also located on the gauge side of rail 62, as shown in fig. 4B. In one embodiment, the electromagnetic radiation is projected onto the guide wheel 60 in a pattern, such as a moire pattern (moire). In such a case, one or more deformations of the pattern may reveal the state of stress and/or other imperfections in the guide wheels 60. Alternatively, another solution may utilize a series of laser micrometer devices through the rail 62 to detect changes in elevation.

Additionally, embodiments of the present invention may incorporate non-laser based illumination. For example, one or more bright Light Emitting Diodes (LEDs) and/or halogen lights may illuminate the guide wheel 60 from the field side of the guide 62 in a strobed or continuous manner. In an embodiment, glancing illumination (such as diffuse glancing illumination) is used to enhance one or more properties of the rail wheel 60. In this regard, FIG. 6 shows an illustrative environment 10C that includes an alternative illumination configuration for obtaining image data of the guide rail wheel 60, according to an embodiment of the invention. In this case, illumination source 94 is diffuse and substantially constant along distance C. Illumination source 94 may be configured to emit diffuse radiation directed upward. As the guide wheel 60 moves through the environment 10C, the diffuse light will illuminate a portion of the tread surface and field side of the guide wheel 60, where the end points of the illuminated portion are swept only by diffuse radiation (e.g., impinging from an acute angle). As used herein, a surface is glancing with radiation when the angle between the surface and the radiation is 30 degrees or less.

By positioning the illumination source 94 proximate to the rail 62 and projecting diffuse light onto the wheel 60, defects tend to be highlighted by techniques known in the art of machine vision, such as shapes from shadows. These shadows can be particularly pronounced in areas of the tread surface that are glancing by diffuse radiation. One or more imaging devices 96 are disposed on the field side of the guideway to image the wheel 60 as the wheel 60 moves through the at least one circumferential path C. The image thus obtained will tend to highlight very fine defects, such as micro cracks, by placing these defects in shadow.

Returning to fig. 4A-4B, each imaging device 96 may include any combination of known imaging electronics, optics (e.g., one or more lenses), and a camera chassis. The optics may include any configuration suitable for the particular environment 10A. In any case, each imaging device 96 may include a standard digital camera or a high speed profiling (profiling) camera connected to the computing device 14 and/or the transfer module 38 (fig. 1) using a Universal Serial Bus (USB), ethernet, or the like. Alternatively, imaging device(s) 96 may include a line scan camera, an analog camera, and/or another type of camera that includes sufficient resolution and speed to acquire image data suitable for analysis in a particular application. In one embodiment, rail wheels 60 may move at speeds up to approximately thirty miles per hour (e.g., fifty kilometers per hour). The maximum speed of the wheels 60 along the rails 62 will determine the performance required for the type of imaging device being used. Further, it is understood that each imaging device 96 includes other functional requirements for machine vision applications, such as exposure control, progressive scan (progressive scan), anti-blooming (anti-blooming), and so forth.

The imaging electronics may include support electronics and an image sensor, such as a CCD chip, whose sensing area is typically square or substantially rectangular. However, as can be seen in fig. 5, the region of interest in the image data (e.g., the region of the guide wheel 60 that intersects the ray 100) is longer in the horizontal direction than in the vertical direction. In this regard, imager chips having much larger horizontal to vertical aspect ratios (e.g., 2 to 1) may be selected to emphasize the horizontal resolution of the system. To minimize the number of imaging devices 96 required to image the entire circumference of the largest wheel 60 as the largest wheel 60 travels through at least one perimeter length path, non-standard lens-to-imaging device mounting methods, such as bellows (bellows) or Scheimpflug (Scheimpflug) adapters, may increase the effective field of view of the camera without the reduced image resolution that would result from using only wider angle lenses.

It is understood that many other optical arrangements (such as fresnel lenses or cylindrical lenses) may produce advantageous imaging features, as will be appreciated by those skilled in the art.

Returning to fig. 4A and 4B, while each imaging device 96 may generate color and/or monochrome images based on visible light, it is understood that one or more imaging devices 96 may generate images based on electromagnetic radiation in the visible, near infrared, ultraviolet, X-ray, and/or other portions of the electromagnetic spectrum.

In this regard, each illumination device 94 may illuminate the rail wheel 60 using any configuration of one or more electromagnetic radiation based illumination solutions that may then be used by a corresponding electromagnetic radiation based imaging device 96 to obtain image data. The use of other types of invisible illumination may enable the imaging device 96 to obtain image data that may be used to measure various attributes of the rail wheel 60 that are not revealed by visible light. For example, the use of image data obtained based on infrared light may be used to detect temperature differences between various surfaces, which may indicate overheating due to one or more defects (e.g., flat spots). Similarly, image data based on infrared or X-ray radiation may be used to measure one or more internal properties of the rail wheel 60, which in turn may be used to determine one or more sub-surface defects of the rail wheel 60 that are hidden from visible light.

Additionally, additional data about the guide wheel 60 may be extracted from the multi-spectral image data. In particular, one or more illumination devices 94 may illuminate the rail wheel 60 with electromagnetic radiation in different portions of the electromagnetic spectrum and/or with electromagnetic radiation-based and non-electromagnetic radiation-based illumination, while one or more imaging devices 96 obtain image data for each illumination solution. The measurement module 44 (fig. 1) may combine the image data using any known image fusion technique and analyze the resulting multi-spectral image data. For example, measurement module 44 may use a combination of visible light and 3D laser imagery in the detection of flat spots. By identifying both the height differences of the guide wheels 60 (e.g., the height differences may result in chords of different lengths) and/or shadow patterns that may be present due to defects, the detection of micro-cracks and other tread defects may be made more reliable, robust, and/or accurate. It is understood that this example is merely illustrative of many potential multi-spectral applications that will be recognized by those skilled in the art. In this regard, the image data may be generated based on any combination of electromagnetic radiation based illumination solutions.

In any event, returning to fig. 1, transfer module 38 transfers image data captured by imaging module 36 to computing device 14 for storage and/or processing by processing system 40. Additionally, the transmission module 38 may transmit additional data about each wheel 60 (fig. 2) to the computing device 14. For example, the transfer module 38 may include a timestamp of the image data, the number of wheels 60 in a series of wheels, the side of the pair of tracks 62 (fig. 2) on which the wheels 60 are located, an identifier of the particular imaging device(s) 96 (fig. 4) that acquired the data, and so forth. In this regard, the transfer module 38 may include a computing device disposed within or near the

housings

90A, 90B and in communication with the imaging device 96. Alternatively, each illumination device 94 (fig. 4) and/or imaging device 96 may be in direct communication with computing device 14 and/or controlled by computing device 14. In this case, transfer module 38 may be implemented as part of computing device 14, e.g., as a module in handler 40. Regardless, the processing program 40 may receive the image data and/or additional data, and process the image data and/or additional data, and/or store the image data and/or additional data as the wheel data 50.

After installation, calibration module 41 may calibrate capture system 30. In this regard, calibration module 41 may perform a series of calibration operations that may be performed with and/or without the assistance of user 16. For example, the calibration module 41 may obtain a set of baseline images of known calibration targets placed on the guide rail in place of the wheels 60 present during actual measurements. The set of baseline images is processed by calibration module 41 to determine a mapping that transforms the measurement images into Cartesian coordinate data over an entire measurement volume (volume) for each imaging device 96 and/or illumination device 94 in capture system 30. In this regard, the calibration module 41 may account for any variations in the field of view between the imaging devices 96 (fig. 4).

In addition, the calibration module 41 may obtain image data of one or more "known good" rail wheels 60. This image data may be analyzed and processed as described herein to determine whether all modules/systems in environment 10 are functioning properly and producing correct results. When one or more errors are detected, the corresponding module/system may be adjusted and the image data may be reacquired until all modules/systems generate the correct results. When adjusting the operation of one or more modules/systems based on one or more conditions (such as lighting, speed, etc.), the calibration module 41 may obtain image data of the rail wheel 60 for a variety of changes in each condition in order to confirm/adjust the proper operation of all modules/systems in the environment 10 in a known manner.

In operation, adjustment module 42 may perform one or more adjustments to the image data. For example, adjustment module 42 may perform a second moment centroid locating (second moment centering) or other estimation algorithm to find the best estimate of the sub-pixel location of the center of the laser line for the case of laser illumination. Additionally, the adjustment module 42 may enhance/manipulate the contrast and/or brightness of the image data to remove noise or compensate for low illumination, glare, surface conditions of the wheel 60, and the like. In this regard, the adjustment module 42 may implement any combination of known algorithms as desired for a particular application. Subsequently, the adjustment module 42 may store the adjusted image data as wheel data 50.

In any case, the measurement module 44 may extract various measurements from the image data, which are then stored as wheel data 50. In one embodiment, the measurement module 44 initially determines the position of the guide wheel 60 (FIG. 2) in a particular image. For example, in one embodiment, as the wheel 60 moves along the rail 62, the wheel may appear to move diagonally across the field of view of the image. The measurement module 44 may examine a particular region of the image for known features, such as edges, changes in the light rays 102 (fig. 5), and/or other features that indicate the position of the rail wheel 60 in the field of view. Also, as the wheel 60 moves through the field of view of the imaging device 96, the top edge of the rail 62 will be in a fixed and unique position in each image, so the edge of the rail 62 (fig. 2) can be used as a baseline for detecting the rail wheel 60.

When the guide wheel 60 (fig. 2) is present, the measurement module 44 may extract a portion of the wheel 60 from each of the plurality of images of the guide wheel 60. For example, FIG. 7 shows detection of wheel 60 in images 120A-120D acquired by imaging device 96 in illustrative environment 10D, according to one embodiment. In FIG. 7, images 120A-120D show various illustrative locations at which the rail wheel 60 may be imaged by the imaging device 96. As illustrated, the imaging device 96 may be oriented to acquire image data at a relatively small angle relative to the path of travel of the rail wheel 60. In one embodiment, the angle is less than forty-five degrees. Using the calibration data, measurement module 44 may locate the boundaries of the portion of wheel 60 present in each of images 120A-120D. Using standard image processing techniques, for each of the rail wheel images 120A-120D, the measurement module 44 may extract features in the wheel section 60 from the image data.

With respect to fig. 8A-8C, a process is illustrated whereby desired features in the wheel 60 are culled from the wheel data 50 using image processing operations known to those skilled in the art. More particularly, FIG. 8A depicts an image 130 of the wheel 60 having a defect desired to be measured. Fig. 8B shows an image 134, which image 134 is the result of a 3D scan of wheel 60 by the imaging device according to an embodiment. The individual scans 136 shown in the exploded view of the area of the image 134 may correspond to the set of light rays 102 shown and described in connection with fig. 5, which set of light rays 102 may be generated on the wheel 60 as the wheel 60 moves along the guide rail 62. The 3D information developed for each point on the wheel 60 contained in the line 102 projected onto the wheel 60 by the illuminator 94 may be used for further image processing. Fig. 8C shows a processed image 138 depicting features extracted from the 3D data of image 130 and/or image 134 by 3D image processing operations known to those skilled in the art. The processed image 138 may be stored as the wheel data 40 for the wheel 60. Returning to FIG. 1, defect module 46 may determine whether one or more defects are present in the wheel based on wheel data 50 and/or the measured characteristics.

With respect to fig. 9, an alternative embodiment environment 10E is shown in which the wheels 60 are not imaged as the wheels 60 move along the rails 62, but are imaged while held and rotated in a rest position. Figure 9 illustrates such an embodiment as may be seen in a wheeled store. The support structure 160 houses the

housings

90C, 90D, each of which housings 90C, 90D may contain the illuminators and cameras described herein in position over the collection of rails 62 running through the wheel store. The wheels 60 passing along the guide rails 62 will be gripped and lifted by the mechanism 162 and assisted by the jacks and support structure 164.

Mechanism 162 includes the ability to apply a force to wheel 60 in order to rotate it. This rotation allows the entire surface of wheel 60 to be imaged using illumination device 94 and camera 96 as described herein. For example, when one or more light rays are directed at the wheel to form a chord on the side surface of the wheel, the chord will be positioned at a substantially constant distance from the center of the wheel. Changes in the height of the chord may indicate one or more defects in the wheel. When illuminated with diffuse radiation, the illumination device 94 and camera 96 may be oriented to acquire image data corresponding to edges of the illuminated portion of the wheel that are only glancing to the radiation, producing enhanced shadow data.

The jack and support structure 164 both assist in lifting and provide safety against very heavy wheels falling out of the grip of the mechanism 162. The operation of and power to the systems in the housing 90, the mechanism 162 and the jack and support structure 164 may be guided by appropriate systems in the housing 166.

As discussed herein, data collected from wheel 60 may be provided to computing device 14 for storage and/or further processing. After inspection, the wheels 60 are returned to the rails 62 and may be routed to a car for use, or to a finishing station for repair/reconditioning, or may be routed to a discard (disposal) area if a fatal fault is found. In this environment 10E, both wheel defects and wheel measurements may be required at various times in the process of restoring a damaged wheel to an operational state. The illuminator and imaging device may be arranged relative to the wheel 60 in any of the configurations previously shown in fig. 4A-7.

It is understood that the various embodiments described and other variations apparent to those skilled in the art may be advantageously combined to develop a more comprehensive identification and measurement of defects in the guide rail wheel 60. For example, horizontal and vertical line laser illumination and diffuse illumination may be employed in any combination. Other variations, such as the projection of a horizontal line depicted in FIG. 4A, may be altered to project a line at an angle relative to horizontal to improve the detection of fine details required in some applications.

In any event, when defect module 46 (fig. 1) detects the presence of one or more defects in rail wheel 60, condition module 48 (fig. 1) may determine an operating condition of rail wheel 60, e.g., whether rail wheel 60 is safe for continued operation. In this regard, condition module 48 may determine a size/severity of the defect and compare the size/severity to a level acceptable for continued operation of rail wheel 60. When the defect exceeds an acceptable level, condition module 48 may indicate that the rail wheel 60 is unsafe for continued operation. Additionally, when the defect is within an acceptable but high range, condition module 48 may generate a warning regarding the use of the rail wheel 60 and may conduct manual (e.g., visual) or computer-assisted additional checks to ensure that the rail wheel 60 remains safe for continued operation.

It is understood that the embodiments described with respect to fig. 4A-7 may be advantageously combined in any combination to achieve the objectives of a particular application.

While shown and described herein as a method and system for measuring a wheel, it is understood that the invention also provides various alternative embodiments. For example, in one embodiment, the invention provides a computer readable medium comprising computer program code to enable a computer infrastructure to evaluate a wheel. To this extent, the computer-readable medium includes program code, such as handler 40 (FIG. 1), which implements each of the various process steps of the invention. It is understood that the term "computer-readable medium" comprises one or more of any type of physical embodiment of the program code. In particular, the computer-readable medium can comprise program code embodied on one or more portable storage articles of manufacture (e.g., a compact disc, a magnetic disk, a tape, etc.), on one or more data storage portions of a computing device, such as memory 22A (FIG. 1) and/or storage system 22B (FIG. 1) (e.g., a fixed disk, a read-only memory, a random access memory, a cache memory, etc.), and/or the like.

In another embodiment, the invention provides a method of generating a system for evaluating a wheel. In this case, a computer infrastructure, such as computer infrastructure 12 (FIG. 1), can be obtained (e.g., created, maintained, having been made available to, etc.) and one or more systems for performing the process steps of the invention can be obtained (e.g., created, purchased, used, modified, etc.) and deployed to the computer infrastructure. In this regard, the deployment of each system may include one or more of the following: (1) installing program code on the computing device from the computer-readable medium, such as installing handler 40 (FIG. 1) on computing device 14 (FIG. 1); (2) adding one or more computing devices to a computer infrastructure, such as one or more of the devices in capture system 30 (FIG. 1); and (3) incorporating and/or modifying one or more existing systems of the computer infrastructure to enable the computer infrastructure to perform the process steps of an embodiment of the invention.

In yet another embodiment, the present invention provides a business method that performs the process steps of the present invention based on subscriptions, advertisements, and/or fees. That is, the service provider may provide the evaluation of the wheels as described above. In this case, the service provider can manage (e.g., create, maintain, support, etc.) a computer infrastructure, such as computer infrastructure 12 (FIG. 1), that performs the process steps of the invention for one or more customers. In return, the service provider can receive payment from the customer(s) under a subscription and/or fee agreement, and/or the service provider can receive payment from the sale of advertising space to one or more third parties.

As used herein, it is understood that the terms "program code" and "computer program code" are synonymous and mean any expression, in any language, code or notation, of a set of instructions intended to cause a computing device to perform a particular function either directly or after any combination of the following: (a) conversion to another language, code or notation; (b) replication in different material forms; and/or (c) decompression. In this regard, program code may be implemented as one or more types of program products, such as an application/software program, component software/a library of functions, an operating system, a basic I/O system/driver for a particular computing and/or I/O device, and the like.

As used herein, unless otherwise specified, the term "set" means one or more (i.e., at least one) and the phrase "any solution" means any now known or later developed solution. The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Furthermore, the terms "comprising," "including," "having," and their derivatives, when used in this specification, specify the presence of stated features, but do not preclude the presence or addition of one or more other features and/or groups thereof. Still further, the term "substantially" means within a margin of error defined by physical limitations of the embodiment. In one embodiment, "substantially" means within +/-one percent.

The foregoing description of various aspects of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.

Claims

1. A method of evaluating a wheel, the method comprising:

illuminating an area in which a wheel is rotating, wherein the illumination comprises at least one light sheet, wherein each light sheet is configured to intersect a side surface of the wheel, thereby forming a chord on the side surface, and to intersect a tread surface of the wheel positioned on at least one side of the chord, wherein at least one of: the chord is positioned at a substantially constant distance from a center of the wheel as the wheel rotates in the region, or the chord forms a segment having a substantially constant height on the side surface of the wheel as the wheel rotates in the region;

obtaining image data of the wheel as the wheel rotates in the region, wherein the image data comprises a plurality of images acquired at different times while the wheel is positioned within the region, wherein the plurality of images comprises a plurality of images including a region of the tread surface of the wheel that intersects at least one of a set of rays; and

evaluating the tread surface of the wheel based on the image data.

2. The method of claim 1, wherein the illuminated area corresponds to a path through which the wheel is moving.

3. The method of claim 2, wherein the illuminated area has a length of at least one circumference of the wheel.

4. The method of claim 2, wherein illuminating comprises emitting at least one sheet of light substantially parallel to a path through which the wheel is moving.

5. The method of claim 1, wherein the image data is acquired by at least one imaging device oriented at an angle of less than forty-five degrees relative to a path through which the wheel is moving.

6. The method of claim 1, wherein the plurality of images including regions of the tread surface of the wheel that intersect at least one of the sets of rays includes image data for substantially an entire perimeter of the tread surface of the wheel.

7. The method of claim 6, wherein the image data of the wheel is obtained from multiple passes of the wheel along a path.

8. The method of any of claims 1 to 7, further comprising illuminating the tread surface of the wheel with diffuse radiation, wherein imaging comprises acquiring image data including portions of the tread surface glared by the diffuse radiation.

9. A system for evaluating a wheel, the system comprising:

a set of lighting devices configured to illuminate an area in which a wheel is rotating, wherein the set of lighting devices emits at least one light sheet configured to intersect a side surface of the wheel, thereby forming a chord on the side surface, and to intersect a tread surface of the wheel positioned on at least one side of the chord, wherein at least one of: the chord is positioned at a substantially constant distance from the center of the wheel as the wheel rotates in the region, or the chord forms a segment having a substantially constant height on a side surface of the wheel as the wheel rotates in the region;

a set of imaging devices configured to acquire image data of the wheel as the wheel rotates in the region, wherein the image data comprises a plurality of images acquired at different times when the wheel is positioned within the region, wherein the plurality of images comprises a plurality of images including regions of the tread surface of the wheel that intersect at least one of a set of rays; and

means for evaluating the tread surface of the wheel based on the image data.

10. The system of claim 9, wherein the set of illumination devices is configured to illuminate a path through which the wheel is moving.

11. The system of claim 10, wherein the path has a length of at least one circumference of the wheel.

12. The system of claim 10, wherein the set of illumination devices emits the at least one sheet of light substantially parallel to a path through which the wheel is moving.

13. The system of claim 9, wherein the set of imaging devices are oriented at an angle of less than forty-five degrees relative to a path through which the wheel is moving.

14. The system of claim 9, wherein the plurality of images including a region of the tread surface of the wheel that intersects at least one of the sets of rays includes image data for substantially an entire circumference of the tread surface of the wheel acquired during a single pass of the wheel through the region.

15. The system of any of claims 9 to 14, further comprising a second set of illumination devices configured to illuminate the tread surface of the wheel with diffuse radiation, wherein the set of imaging devices acquires image data comprising portions of the tread surface glancing with the diffuse radiation.

16. A system for evaluating a wheel, the system comprising:

a set of illumination devices configured to illuminate at least a tread surface of the wheel with diffuse radiation;

a set of imaging devices configured to acquire image data of the wheel as the wheel rotates in the region, wherein the image data includes a plurality of images acquired at different times while the wheel is positioned within the region, wherein the set of imaging devices acquires image data including portions of the tread surface glancing off of the diffuse radiation; and

means for evaluating the tread surface of the wheel based on the image data.

17. The system of claim 16, wherein the set of imaging devices are oriented at an angle of less than forty-five degrees relative to a path through which the wheel is moving.

18. The system of claim 16 or 17, further comprising a set of illumination devices configured to illuminate an area in which a wheel is rotating, wherein the set of illumination devices emits at least one light sheet configured to intersect a tread surface of the wheel, wherein at least one of: the height of intersection with the tread surface is positioned at a substantially constant distance from the center of the wheel as the wheel rotates in the region, or the height of intersection with the tread surface is positioned at a substantially constant height above the path traveled by the wheel.